The present invention relates to semiconductor transducers and more particularly to an apparatus and method for producing a high temperature, surface mounted pressure transducer, an ultra thin surface mounted pressure transducer suitable for use in a high temperature high, acceleration environment.
Semiconductor pressure transducers are employed in the measurement of pressure in numerous types of applications and environments. Many pressure transducers employ a relatively thin diaphragm fabricated from semiconductor materials such as silicon. Upon the diaphragm is deposited or otherwise formed a piezoresistive strain gage configuration, such as a bridge circuit, where the resistors associated with the bridge exhibit a change in resistance according to the deflection of the diaphragm. By monitoring the change in resistance, one obtains an output voltage indicative of the applied pressure or force. The operation of such transducers is very well known. Pressure transducers capable of operating at high temperatures as, for example, at 900xc2x0 F., and having small physical dimensions, particularly thickness, which are highly desired in various applications. For instance, the measurement of air or other fluid flow across turbine blades in a jet engine can occur in a high temperature, high acceleration environment. Moreover, the mounting of such a transducer on the turbine blade or similar structure should perturb the fluid flow as little as possible thus implying a very thin transducer.
Reference is made to U.S. Pat. No. 5,973,590 issued on Oct. 26, 1999 entitled, xe2x80x9cUltra Thin Surface Mount Wafer Sensor Structures and Methods of Fabricating the Samexe2x80x9d to A. D. Kurtz et al. and is assigned to Kulite Semiconductor Products, Inc., the assignee herein, as well as U.S. Pat. No. 6,210,989 entitled, xe2x80x9cUltra Thin Surface Mount Wafer Sensor Structure and Methods for Fabricating the Samexe2x80x9d which issued on Apr. 3, 2001 to A. D. Kurtz et al. As will be explained, the sensor depicted in those patents is used in the present invention together with additional components to provide a high temperature surface mounted transducer. In addition, an acceleration compensated sensor if desired, can be used which is fabricated using the methods taught in U.S. Pat. No. 6,293,154 entitled, xe2x80x9cVibration Compensated Pressure Sensing Assemblyxe2x80x9d which issued on Sep. 25, 2001 to A. D. Kurtz et al and is assigned to the assignee herein. The surface mounting of a transducer is extremely desirable, as it can be accommodated by a flat-pack configuration, making it adaptable for use in many different environments. Such uses are in the automotive, aeronautical, and other industries to provide a high temperature transducer in a flat-pack configuration which is compact and easy to install. Such uses include the monitoring of turbine blade airflow or airflow over rocket surfaces and so on.
A high temperature transducer structure comprises an insulator planar member having disposed on a top surface a plurality of depressions for accommodating contact areas, each depression has an associated metalized channel directed from the depression to a contact end of the planar member. A silicon sensor member has a deflectable diaphragm area associated with piezoresistive sensors. The active area is surrounded by a non-active area, the non-active area has a plurality of contacts coupled to the piezoresistive sensors and is directed through contact apertures to a contact surface of the silicon member. The plurality of contacts are arranged in congruency with the plurality of depressions so that each contact of the sensor member is positioned in an associated depression when the sensor member is positioned on the planar member. There are means for securing the sensor member to the planar member to form a composite member and a metallic flat housing has external leads at a terminating end. The housing accommodates the composite member which has an associated external lead which corresponds with an associated metalized channel for connecting the lead to the channel when the corporate member is located in the housing.